• 대한치과교정학회지
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• 제45권6호
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• pp.275-281
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• 2015

Objective: To assess the accuracy of anterior tooth movement using clear aligners in integrated three-dimensional digital models. Methods: Cone-beam computed tomography was performed before and after treatment with clear aligners in 32 patients. Plaster casts were laser-scanned for virtual setup and aligner fabrication. Differences in predicted and achieved root and crown positions of anterior teeth were compared on superimposed maxillofacial digital images and virtual models and analyzed by Student's t-test. Results: The mean discrepancies in maxillary and mandibular crown positions were $0.376{\pm}0.041mm$ and $0.398{\pm}0.037mm$, respectively. Maxillary and mandibular root positions differed by $2.062{\pm}0.128mm$ and $1.941{\pm}0.154mm$, respectively. Conclusions: Crowns but not roots of anterior teeth can be moved to designated positions using clear aligners, because these appliances cause tooth movement by tilting motion.

• 대한치과교정학회지
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• 제51권1호
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• pp.32-42
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• 2021

Objective: To investigate the three-dimensional forces created by clear aligners on mandibular teeth during differential activation with en-masse retraction and/or intrusion in vitro. Methods: Six sets of clear aligners were designed for differential en-masse retraction and/or intrusion procedures in a first premolar extraction model. Group A0 was a control group with no activation. Groups A1-5 underwent different degrees of retractions and/or intrusions. Each group consisted of 10 aligners. Aligner forces were measured on a multi-axis force/torque transducer measurement system in real-time. Results: In the en-masse retraction groups (A1 and A2), lingual and extrusive forces were observed on the incisors; the canines mainly received distal forces; intrusive forces were seen on the second premolars; and the molars received mesial forces. In the en-masse retraction and intrusion groups (A3, A4, and A5), incisors also received lingual and extrusive forces; canines received distal and intrusive forces; mesial and extrusive forces were seen on the second premolars; and the second molars received distal and intrusive forces. The vertical forces on the incisors did not differ significantly among groups A1, A3, and A5. However, the vertical forces on the second premolars reversed from intrusion in group A1 to extrusion in groups A3 and A5. Conclusions: With clear aligners, the "bowing effect" is seen during en-masse anterior teeth retraction and can be partially relieved by performing en-masse retraction accompanied by anterior teeth intrusion. Vertical control of incisors remained unsolved during en-masse retraction, even when intrusive activation was added to the anterior teeth.

• 대한치과교정학회지
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• 제33권1호
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• pp.21-29
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• 2003

최근 컴퓨터 소프트웨어의 발전으로 환자의 모형을 scanning하여 3차원 가상 모델을 만드는 것이 가능하게 되었다. 이러한 모델은 컴퓨터로 처리되어 치료 시작부터 끝까지 여러 단계의 치아 이동이 이루어지고, 치아 이동의 각 단계별로 stereolithographic model이 만들어 지는데, 이는 일련의 투명하고 얇은 overlay 장치를 제작하는 기초가 된다. 계획된 치아 이동의 단계에 따라 치아를 움직이기 위해서는 환자가 장치를 항상 사용해야 하며, 중정도의 crowding과 공간 폐쇄는 이 장치로 치료가 용이하다는 것이 입증되었다. 지금까지 이 장치를 경험해 본 결과, 고정성 교정장치에 비해 환자가 불편을 덜 느끼고 심미성과 구강 청결이 좋아 환자의 협조도가 뛰어 났다. 이 장치는 완전히 맹출된 영구치열 환자에서 부정교합에 대한 또 하나의 유용한 접근법이라 할 수 있다.

• 대한치과교정학회지
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• 제51권5호
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• pp.329-336
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• 2021

Objective: To compare the magnitude of external apical root resorption (EARR) 6 months after starting orthodontic treatment using orthodontic aligners (OAs) and fixed appliances (FAs). Methods: This parallel randomized clinical trial included 40 patients randomized into two groups: OA group (n = 20, 160 incisors) and FA group (n = 20, 160 incisors). For evaluation of the tooth length, periapical radiographs and standardized linear measurements of the maxillary and mandibular incisors were acquired before (T0) and 6 months after treatment initiation (T1). EARR was calculated through the difference in length between the two time points (T1-T0). Statistical comparisons were performed by means of using t-tests, chi-squared test and covariance analysis (a = 5%). Results: Rounding of the root apex was observed in both groups; the resorption involved 2.88% of the root length, so 97.12% of the tooth length remained intact. Intragroup comparisons between the two time points revealed a significant difference, with (T1-T0) ranging from -0.52 to -0.88 mm in the FA group and from -0.52 to -0.85 mm in the OA group. In the intergroup comparisons, only tooth #21 presented a statistically significant difference (OA: -0.52 ± 0.57 mm, FA: -0.86 ± 0.60 mm); however, the overall differences between groups were not clinically relevant, ranging from 0.03 to 0.35 mm. Conclusions: OA and FA treatment resulted in a similar degree of EARR in the maxillary and mandibular incisors at 6 months after treatment initiation. However, the amount of resorption was small and does not impair tooth longevity.

• 치위생과학회지
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• 제23권4호
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• pp.245-254
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• 2023

Background: This study aimed to determine the skeletal and dental effects in pediatric and adolescent Korean patients with Class II Division 1 malocclusion treated using the Invisalign Mandibular Advancement (MA^®) appliance. Methods: The study included patients aged 6 to 18 years who received orthodontic treatment with the MA^® appliance for Class II Division 1 malocclusion at the Department of Pediatric Dentistry, Wonkwnag University Daejeon Dental Hospital, between July 1, 2018, and December 31, 2021. The treatment group consisted of 20 patients, 10 boys and 10 girls. The control participants were also 10 boys and 10 girls. Lateral cephalometric radiographs were taken before and after treatment, and 41 measurements of skeletal and dental changes were measured and analyzed using the V-Ceph^TM 8.0 (Osstem Implant). All analyses were performed using SPSS software (IBM SPSS for Windows, ver 26.0; IBM Corp.), and statistical significance was tested using paired and independent samples t-tests for within-group and between-group comparisons, respectively. Results: The patients in the treatment group showed significant decreases in ANB (A point, Nasion, B point), maxillary protrusion, maxillary anterior incisor labial inclination, and maxillary protrusion after treatment. However, when compared with the growth changes observed in the control group, only ANB and maxillary protrusion decreased, with no significant differences in SNA, SNB, and mandibular length. Conclusion: Collectively, the results of this study confirm that the use of MA^® appliance in pediatric and adolescent Korean patients with Class II Division 1 malocclusion results in a reduction of anteroposterior skeletal and dental disharmony.

• 대한심미치과학회지
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• 제27권2호
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• pp.82-96
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• 2018

3D 프린팅은 삼차원 이미지 정보를 이용하여 레이어로 분할한 후 선택한 소재를 적층하여 가공하는 방법을 말한다. 소재를 적층하는 방법에 따라 다양한 종류의 3D 프린팅이 존재하는데 최근 치과분야에서는 SLA방식과 DLP방식으로 광원을 이용한 경화를 통해 적층 가공하는 3D 프린팅이 널리 보급되어 사용되고 있다. 전악 범위의 3D프린팅 치과용 모델은 전통적인 인상 채득으로 제작된 스톤모델보다는 다소 정확성이 부족한 것으로 보고되었으나, 같은 STL파일을 이용하여 4분악 범위를 3D 프린팅한 모델은 밀링 방법으로 가공한 모델보다 정확하였다. 디자인 소프트웨어의 활용도에 따라 보철치료의 진단, 임시 보철물의 제작, 의치의 제작이 가능하였다. 교정에서는 투명 교정 모델과 브라켓 간접 부착을 위한 트레이 제작이 가능하였다. 임플란트 수술에 있어서 CT를 기반으로 한 정확한 위치에 임플란트를 식립하는 가이드 제작에 활용하고 있다. 출력 방식의 발전으로 인하여 3D 프린터의 출력시간이 계속적으로 단축되고 있으며, 이로 인해 치과 진료실 내에서 3D 프린터가 기존의 전통적인 가공 방법을 대체할 수 있을 것으로 기대한다.